Distally-extending muscle fibers across involved joints: study of long muscles and tendons of wrist and ankle in late-term fetuses and adult cadavers / 대한해부학회지

It is unclear whether forearm and crural muscle fibers extend distally across the wrist and ankle joints, respectively.We hypothesized, in late-term fetuses, an over-production of muscle bellies extending over the joint. Muscle fibers in histological sections from unilateral wrists and ankles of 16 late-term fetuses (30–40 weeks) were examined and compared with 15 adult cadavers. Muscle fibers of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) in fetuses, especially muscle bellies to the third and fourth fingers, were found to extend far distally beyond the radiocarpal joint.The extensor digitorum and extensor pollicis longus on the extensor side of the wrist were found to carry distally-extending muscle fibers, but these fibers did not extend beyond the distal end of the radius. In the ankle, most muscle bundles in the flexor hallucis longus (FHL), fibularis brevis (FB) and extensor digitorum longus extended distally beyond the talocrural joint, with most FB muscle fibers reaching the level of the talocalcaneal joint. In adult cadavers, muscle fibers of the FDP and FHL did not reach the levels of the radiocarpal and talocrural joints, respectively, whereas the FB muscle belly always reached the talocalcaneal joint. Similarly, some of the FDS reached the level of the radiocarpal joint. Generally, infants’ movements at the wrist and ankle could result in friction injury to over-extended muscle. However, the calcaneal and FDP tendons might protect the FB and FDS tendons, respectively, from friction stress.

Development and growth of the human fetal sacroiliac joint revisited: a comparison with the temporomandibular joint / 대한해부학회지

The human fetal sacroiliac joint (SIJ) is characterized by unequal development of the paired bones and delayed cavitation. Thus, during the long in utero period, the bony ilium becomes adjacent to the cartilaginous sacrum. This mor phology may be analogous to that of the temporomandibular joint (TMJ). We examined horizontal histological sections of 24 fetuses at 10–30 weeks and compared the timing and sequences of joint cartilage development, cavitation, and ossification of the ilium. We also examined histological sections of the TMJ and humeroradial joint, because these also contain a disk or disk-like structure. In the ilium, endochondral ossification started in the anterior side of the SIJ, extended posteriorly and reached the joint at 12 weeks GA, and then extended over the joint at 15 weeks GA. Likewise, the joint cartilage appeared at the anterior end of the future SIJ at 12 weeks GA, and extended along the bony ilium posteriorly to cover the entire SIJ at 26 weeks GA. The cavitation started at 15 weeks GA. Therefore, joint cartilage development seemed to follow the ossification of the ilium by extending along the SIJ, and cavitation then occurred. This sequence “ossification, followed by joint cartilage formation, and then cavitation” did not occur in the TMJ or humeroradial joint. The TMJ had a periosteum-like membrane that covered the joint surface, but the humeroradial joint did not. After muscle contraction starts, it is likely that the mechanical stress from the bony ilium induces development of joint cartilage.

Umbilical cord vessels other than the umbilical arteries and vein: a histological study of midterm human fetuses / 대한해부학회지

At birth, the umbilical cord contains various types of thin vessels that are near and outside the umbilicus and separate from the umbilical arteries and vein. These vessels are regarded as the remnant “vitelline vessels” and are often called “umbilical vessels”, although this terminology could lead to confusion with the true umbilical arteries and vein. No study has yet comprehensively examined these vessels using histological sections. Our examination of these vessels in 25 midterm fetuses (gestational age: 10–16 weeks) led to five major findings: (i) all specimens had umbilical branches of the inferior epigastric artery; (ii) 5 specimens had vitelline vein remnants; (iii) 4 specimens had a thin artery originating from the left hepatic artery that ran along the umbilical vein; (iv) 2 specimens had a so-called “para-umbilical vein” that was along the umbilical vein and reached the umbilicus; and (v) all specimens had lymphatic vessels originating from the umbilicus that ran caudally along the umbilical artery. The pelvic vein tributaries were well developed along the intra-abdominal umbilical artery, but did not reach the umbilicus. The lymphatic vessel was distinguished from the veins by an intraluminar cluster of lymphocytes attaching to the endothelium. The arterial branch in the umbilical cord did not accompany veins and lymphatic vessels, in contrast to the mother artery in the rectus abdominis. All these thin vessels seemed to be obliterated when the fibrous umbilical ring grew during late-term. The para-umbilical collateral vein in adults might develop outside the fibrous umbilical ring after birth.

Fetal cervical zygapophysial joint with special reference to the associated synovial tissue:a histological study using near-term human fetuses / 대한해부학회지

Human fetal cervical vertebrae are characterized by the large zygapophysial joint (ZJ) extending posteriorly. During our recent studies on regional differences in the shape, extent, and surrounding tissue of the fetal ZJ, we incidentally found a cervical-specific structure of synovial tissues. This study aimed to provide a detailed evaluation of the synovial structure using sagittal and horizontal sections of 20 near-term fetuses. The cervical ZJ consistently had a large cavity with multiple recesses at the margins and, especially at the anterior end, the recess interdigitated with or were located close to tree-like tributaries of the veins of the external vertebral plexus. In contrast to the flat and thin synovial cell lining of the recess, the venous tributary had cuboidal endothelial cells. No or few elastic fibers were identified around the ZJ. The venous-synovial complex seems to be a transient morphology at and around birth, and it may play a role in the stabilization of the growing cervical ZJ against frequent spontaneous dislocation reported radiologically in infants. The venous-synovial complex in the cervical region should be lost and replaced by elastic fibers in childhood or adolescence. However, the delayed development of the ligament flavum is also likely to occur in the lumbar ZJ in spite of no evidence of a transient venous-synovial structure. The cuboidal venous endothelium may simply represent the high proliferation rate for the growing complex.

Fetal cervical zygapophysial joint with special reference to the associated synovial tissue:a histological study using near-term human fetuses / 대한해부학회지

Human fetal cervical vertebrae are characterized by the large zygapophysial joint (ZJ) extending posteriorly. During our recent studies on regional differences in the shape, extent, and surrounding tissue of the fetal ZJ, we incidentally found a cervical-specific structure of synovial tissues. This study aimed to provide a detailed evaluation of the synovial structure using sagittal and horizontal sections of 20 near-term fetuses. The cervical ZJ consistently had a large cavity with multiple recesses at the margins and, especially at the anterior end, the recess interdigitated with or were located close to tree-like tributaries of the veins of the external vertebral plexus. In contrast to the flat and thin synovial cell lining of the recess, the venous tributary had cuboidal endothelial cells. No or few elastic fibers were identified around the ZJ. The venous-synovial complex seems to be a transient morphology at and around birth, and it may play a role in the stabilization of the growing cervical ZJ against frequent spontaneous dislocation reported radiologically in infants. The venous-synovial complex in the cervical region should be lost and replaced by elastic fibers in childhood or adolescence. However, the delayed development of the ligament flavum is also likely to occur in the lumbar ZJ in spite of no evidence of a transient venous-synovial structure. The cuboidal venous endothelium may simply represent the high proliferation rate for the growing complex.

Heterogeneity of glandular cells in the human salivary glands: an immunohistochemical study using elderly adult and fetal specimens / 대한해부학회지

Using immunohistochemical staining for alpha-smooth muscle actin (alpha-SMA), glial fibrillary acidic protein (GFAP), S100 protein (S100), p63, cytokeratin 14 (CK14), and cytokeratin 19 (CK19), we studied acinar and myoepithelial cells of major and minor salivary glands obtained from 14 donated cadavers (78-92 years old) and 5 donated fetuses (aborted at 15-16 weeks of gestation). CK and p63 expression was investigated only in the adult specimens. SMA was detected in all adult glands as well as in fetal sublingual and pharyngeal glands. GFAP expression was seen in a limited number of cells in adult glands, but was highly expressed in fetal pharyngeal glands. S100-positive myoepithelial-like cells were present in adult minor glands as well as in fetal sublingual and pharyngeal glands. Expression of p63 was evident in the ducts of adult glands. CK14 immunoreactivity was observed in a limited number of glandular cells in adults, in contrast to consistent expression of CK19. In both adults and fetuses, a mosaic expression pattern was usually evident for each of the examined proteins. A difference in immunoreactivity for the nerve markers GFAP and S100 was observed between the major and minor glands. Thus, in the present histologic study, we distinguished between the specific gland types on the basis of their immunohistochemical staining. A mosaic expression pattern suggested that the immunoreactivity against nerve protein markers in myoepithelial cells could not be due to the persistence of neural crest remnants or the physiological status of the gland, such as age-related degeneration.

Influence of developing ligaments on the muscles in contact with them: a study of the annular ligament of the radius and the sacrospinous ligament in mid-term human fetuses / 대한해부학회지

The supinator muscle originates from the annular ligament of the radius, and the muscle fibers and ligament take a similar winding course. Likewise, the coccygeus muscle and the sacrospinous ligament are attached together, and show a similar fiber orientation. During dissection of adult cadavers for our educational curriculum, we had the impression that these ligaments grow in combination with degeneration of parts of the muscles. In histological sections of 25 human fetuses at 10-32 weeks of gestation, we found that the proximal parts of the supinator muscle were embedded in collagenous tissue when the developing annular ligament of the radius joined the thick intermuscular connecting band extending between the extensor carpi radialis and anconeus muscles at 18-22 weeks of gestation, and the anterior parts of the coccygeus muscle were surrounded by collagenous tissue when the intramuscular tendon became the sacrospinous ligament at 28-32 weeks. Parts of these two muscles each seemed to provide a mold for the ligament, and finally became involved with it. This may be the first report to indicate that a growing ligament has potential to injure parts of the "mother muscle," and that this process may be involved in the initial development of the ligament.

Spatial relationship between expression of cytokeratin-19 and that of connexin-43 in human fetal kidney / 대한해부학회지

Connexin-43, a major gap junction protein, and cytokeratin-19, one of the intermediate filament keratins, are known to be markers of well-differentiated epithelium. In this study, we investigated the expression of these markers in the head region, lungs, and abdominal organs of 10 human mid-term fetuses. The expression of connexin-43 was found to be restricted to the dura mater, kidney, and adrenal cortex. In the kidney, we found a clear site-dependent difference in the expression pattern of these markers: connexin-43 expression was observed in the tubules of the renal cortex whereas cytokeratin-19 was strongly expressed in the collecting ducts and renal pelvis. This difference remained unchanged throughout the fetal stages examined. Immunoreactivity was not observed for either of the markers in the intrarenal vessels, including the glomeruli, and mesangial cells. Connexin-43 expression seemed to be restricted to the metanephric vesicle-derived structures that differentiate in the urogenital ridge of the splanchnic mesoderm. The adrenal cortex also originates from the same para-aortic mesoderm. In contrast, in the urogenital organs, cytokeratin-19 seemed to be expressed in ducts derived from the urogenital sinus.

Left testicular artery arching over the ipsilateral renal vein / 亚洲男科学杂志(英文版)

<p><b>AIM</b>To report two cases of the left testicular artery arching over the left renal vein (LRV) before running downward to the testis.</p><p><b>METHODS</b>The subjects were obtained from two Japanese cadavers. During the student course of gross-anatomical dissection, the anatomical relationship between the testicular vessels and the renal vein was specifically observed.</p><p><b>RESULTS</b>The arching left testicular artery arose from the aorta below the LRV and made a loop around the LRV, which appeared to be mildly compressed between the arching artery and the psoas major muscle.</p><p><b>CONCLUSION</b>Clinically, compression of the LRV between the abdominal aorta and the superior mesenteric artery occasionally induces LRV hypertension, resulting in varicocele, orthostatic proteinuria and hematuria. Considering that the incidence of a left arching testicular artery is higher than that of a right one, an arching left artery could be an additional cause of LRV hypertension.</p>